David Alan Black wrote:

# I know this is off-topic, though perhaps it's on-topic in a meta-topic
# kind of way....

It most certainly is (at least now :-) on-topic: 

    The more rapid emergence of Ruby as the world's predominate
    programming language will be facilitated by a theoretically
    practical understanding of the sorts of powerfully useful roles
    that Ruby/XML (which already exists), Ruby/SGML, and Ruby/HTML can
    play, and an understanding of how XML, SGML, and HTML are related
    helps serve this end.

Conrad Schneiker
(This note is unofficial and subject to improvement without notice.)